Climatic consequences of regional nuclear conflicts

Abstract

Abstract. We use a modern climate model and new estimates of smoke generated by fires in contemporary cities to calculate the response of the climate system to a regional nuclear war between emerging third world nuclear powers using 100 Hiroshima-size bombs (less than 0.03% of the explosive yield of the current global nuclear arsenal) on cities in the subtropics. We find significant cooling and reductions of precipitation lasting years, which would impact the global food supply. The climate changes are large and long-lasting because the fuel loadings in modern cities are quite high and the subtropical solar insolation heats the resulting smoke cloud and lofts it into the high stratosphere, where removal mechanisms are slow. While the climate changes are less dramatic than found in previous "nuclear winter'' simulations of a massive nuclear exchange between the superpowers, because less smoke is emitted, the changes are more long-lasting because the older models did not adequately represent the stratospheric plume rise.

Impacts of a nuclear war in South Asia on soybean and maize production in the Midwest United States

“…Atmospheric circulation and associated changes in temperature, precipitation, and solar radiation were simulated by ModelE, a general circulation model (GCM) (Schmidt et al 2006) from the Goddard Institute for Space Studies (Robock et al 2007). For more details on the climate model results, please see Xia and Robock (2012).…”

“…The precipitation anomaly varies the most across sites, followed by temperature and radiation, as indicated by the large spread around the mean value. Robock et al (2007) showed that when averaged globally and annually, the temperature anomaly reduces to −0.5°C in year 10, but anomalies in the Midwest do not exhibit this behavior; even in year 10, the anomalies are noisy, and very cool summers still can occur.…”

“…Temperature displays more negative than positive anomalies, indicating significant cooling through the decade. Solar radiation has a large drop in the first year, recovers gradually through the study period, but remains negative partly because of strong absorption of sunlight by black smoke even after 10 years (Robock et al 2007). The precipitation anomaly varies the most across sites, followed by temperature and radiation, as indicated by the large spread around the mean value.…”

“…The thick black line represents the mean anomaly across the four sites while the broken line around the mean is the standard deviation across all sites. Data from Robock et al (2007) radiation increases, maximum temperatures rise, leading crops to accelerate their GDD accumulation quicker, with fewer calendar days to accumulate biomass. Also, increased radiation associated with increases in maximum temperature and decreases in precipitation may lead to greater evapotranspiration, causing soil moisture stress to increase.…”

“…For the temperature variables and solar radiation, monthly anomalies from Robock et al (2007) were added to daily quantities uniformly over each month. The temperature anomalies were weighted; 80 % of the anomaly was added to the maximum and only 20 % to the minimum temperature, following Robock (1988) and(1991).…”